DIY TAX SERVICES can make filing your yearly returns a virtually fool-proof (albeit still annoying!) experience. Too bad that the seamlessness doesn’t always translate into an error-free return. In 2024, more than a million people had to amend their taxes to correct a mistake, according to the IRS. Getting something wrong could mean a delayed refund, paying more than you owe, being hit with a big bill down the line, or even dealing with an audit. Save yourself the headache by avoiding mistakes in the first place. Here, three common blunders:

Entering Tiny but Major Typos

Many mistakes are just sloppy and totally preventable. The IRS reports that these errors often include misspelling your name (blame it on Clumsy Fingers Syndrome), incorrectly typing your Social Security or bank account number (anyone else miss the number pads on keyboards?), or, if you’re going the pen-and-paper route, simply forgetting to sign in all the right places before heading to the post office. Screwing up the calculations when figuring out your deductions or earned credits is another biggie. In the 2023 tax filing season, the IRS sent 2.2 million notices to taxpayers who had made math errors!

If you slow down, you can avoid these kinds of mistakes, says Mark Steber, chief tax information officer at Jackson Hewitt, a tax preparation service with offices nationwide.

Most tax software will catch math errors, but you should double-check anything you entered manually, especially if the outcome seems wildly off. Rob Burnette, a financial adviser at Outlook Financial Center in Troy, Ohio, says he had a client who accidentally reported paying $170,100 in mortgage interest. It was supposed to be $1,701, but the software misplaced a decimal point, which went unnoticed. “The client saw a huge refund, got excited, and filed,” Burnette says. “Most of it had to be returned.”